I don't think that Korra's OOC characterization can be reasonably handwaved; the author's views on Korra are clearly misguided at best. Said author has gone on record claiming that canon Korra is the sort of person who can only find the strength to defend herself when she's fighting for other people, which is heavily contradicted by both actual canon and Word of Bryke. Once Korra's tendency towards overzealous defense of her own ego is taken from her, what's left can barely even be called Korra anymore.

It's easy to see why the author would do this of course, given that Korra's canon character is an exceptionally bad fit for victimization through stock Domestic Abuse tropes. Not only is she likely to come out as victor in any pure physical confrontation, but her personal hangups in regards to power and control make her highly inclined to escalate attacks against her self-worth into physical violence before they can impact her fighting ability severely enough to lose that advantage. A sadistic creator of sufficient talent might be able to work around that, but it would be both difficult to pull off and highly uncomfortable to write, so it's just easier to weaken Korra. (Of course, flipping the roles would also be easier without destroying canon quite so badly; it's considerably less of a stretch to expand Korra's need for power and control to pathological levels than it is to have her fail to resist attempts at control by someone else)

If the extent of the author's crimes against canon were the creation of a fanfic that's essentially original fiction with character names pasted on, that would be one thing. But the author's insistence that the Abuse Cycle's characterization is based in canon is indefensible.